If you think Viva Pinata is just a silly kids' game that's not worth your hardcore gaming time, you're probably right. Viva Pinata is a very special game that won't appeal to gamers only interested in adrenaline-fueled bullet fests. If you've got an open mind, however, you'll find a uniquely addictive and pleasantly colorful change of pace that scratches that Animal Crossing itch without all the hassle of little dogs yelling at you for not playing in a couple days.
You start with a ramshackle plot of land strewn with garbage and rocky ground and it's your duty to pound the land back into shape, providing a safe haven for the local pinata wildlife. It's a relatively simple concept that ramps up complexity fairly gradually (though seasoned gamers will find that the difficulty level keeps pace nicely after the fairly brief tutorial period).
As a larger variety of pinatas make your garden their home, the business of caring for them becomes a feat similar to juggling fire. See, the pinatas of Viva Pinata aren't necessarily as chummy with each other as they are with you, so you'll spend a good bit of time trying to separate annoyed Buzzlegums from pesky Raisants (an improbably challenging task since Buzzlegums can fly anywhere they want). You could just get rid of the Raisants by smacking them with your shovel, but then your Newtgats would have nothing to eat, and (by extension) no way to get into the romantic mood that enables them to have little Newtgat babies.